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Date:      Mon, 22 Mar 1999 01:55:16 +0100
From:      Pascal Gienger <p@znet.de>
To:        freebsd-isdn@freebsd.org
Subject:   More investigations on the sppp connection-close bug
Message-ID:  <19990322015516.A346@finesse.paul-magazin.de>

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I noticed that the phenomenon begins at the moment when the remote
side requests the termination of the link (timeout of the remote router).

Normally, a request should work like this (authentication is not needed
with this access):

01:43:41.375455 ID-001 LCP: Configure-Request, Magic-Number=2010597547
			 0101 000a 0506 77d7 48ab
01:43:41.386319 ID-001 LCP: Configure-Request, Max-Rx-Unit=1524, Proprietary
			 0101 0011 0104 05f4 1309 0300 c07b 53ea
			 3a
01:43:41.386435 ID-001 LCP: Configure-Reject, Proprietary
			 0401 000d 1309 0300 c07b 53ea 3a
01:43:41.388417 ID-001 LCP: Configure-Ack, Magic-Number=2010597547
			 0201 000a 0506 77d7 48ab
01:43:41.396185 ID-002 LCP: Configure-Request, Max-Rx-Unit=1524
			 0102 0008 0104 05f4
01:43:41.396298 ID-002 LCP: Configure-Ack, Max-Rx-Unit=1524
			 0202 0008 0104 05f4
01:43:41.396510 ID-002 IPCP: IP-Addresses, Src=5.244.72.171, Dst=83.234.58.123
			 0102 0004
01:43:41.408319 ID-001 IPCP: IP-Compression-Protocol
			 0101 0010 0206 002d 0f01 0306 8622 5806
01:43:41.408441 ID-001 IPCP: IP-Compression-Protocol
			 0401 000a 0206 002d 0f01
01:43:41.410247 ID-001 CCP: 
			 0101 0009 1105 0001 04
01:43:41.410299 ID-003 LCP: Protocol-Reject
			 0803 000f 80fd 0101 0009 1105 0001 04
01:43:41.411730 ID-002 IPCP: 
			 0202 0004
01:43:41.468158 ID-002 IPCP: IP-Address=134.34.88.6
			 0102 000a 0306 8622 5806
01:43:41.468287 ID-002 IPCP: IP-Address=134.34.88.6
			 0202 000a 0306 8622 5806

01:45:52.660978 ID-013 LCP: Protocol-Reject
			 080d 000a c029 0501 0004
01:45:53.656332 ID-014 LCP: Terminate-Request
			 050e 0004
01:45:53.658797 ID-003 LCP: Terminate-Request
			 0503 0004
01:45:53.658867 ID-003 LCP: Terminate-Ack
			 0603 0004
01:45:53.664153 ID-014 LCP: Terminate-Ack
			 060e 0004

and the link is down. That's the normal behaviour. But when the remote
side disconnects, the following will occur in subsequent dialup-attempts:

01:46:03.814390 ID-015 LCP: Configure-Request, Magic-Number=2010597547
			 010f 000a 0506 77d7 48ab
01:46:03.824845 ID-001 LCP: Configure-Request, Max-Rx-Unit=1524, Proprietary
			 0101 0011 0104 05f4 1309 0300 c07b 53ea
			 3a
01:46:03.824962 ID-001 LCP: Configure-Reject, Proprietary
			 0401 000d 1309 0300 c07b 53ea 3a
01:46:03.826956 ID-015 LCP: Configure-Ack, Magic-Number=2010597547
			 020f 000a 0506 77d7 48ab
01:46:03.834712 ID-002 LCP: Configure-Request, Max-Rx-Unit=1524
			 0102 0008 0104 05f4
01:46:03.834826 ID-002 LCP: Configure-Ack, Max-Rx-Unit=1524
			 0202 0008 0104 05f4
01:46:03.835091 ID-016 LCP: Terminate-Request
			 0510 0004
01:46:03.845350 ID-001 IPCP: IP-Compression-Protocol
			 0101 0010 0206 002d 0f01 0306 8622 5806
01:46:03.848032 ID-001 CCP: 
			 0101 0009 1105 0001 04
01:46:03.848684 ID-016 LCP: Terminate-Ack
			 0610 0004
01:46:19.301726 ID-017 LCP: Configure-Request, Magic-Number=2010597547
			 0111 000a 0506 77d7 48ab
01:46:19.313196 ID-001 LCP: Configure-Request, Max-Rx-Unit=1524, Proprietary
			 0101 0011 0104 05f4 1309 0300 c07b 53ea
			 3a
01:46:19.313310 ID-001 LCP: Configure-Reject, Proprietary
			 0401 000d 1309 0300 c07b 53ea 3a
01:46:19.315284 ID-017 LCP: Configure-Ack, Magic-Number=2010597547
			 0211 000a 0506 77d7 48ab
01:46:19.323037 ID-002 LCP: Configure-Request, Max-Rx-Unit=1524
			 0102 0008 0104 05f4
01:46:19.323150 ID-002 LCP: Configure-Ack, Max-Rx-Unit=1524
			 0202 0008 0104 05f4
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

After this line, IPCP negotiation should start, but it does not.
I suspect that some sort of state mixes up in this case.
Next weekend I'll have more time to look close at the sources. Perhaps
I'll find something.

01:46:19.323415 ID-018 LCP: Terminate-Request
			 0512 0004

(... and the link is down ...).

If you comment out in if_spppsubr.c the passage where after starting
the authentication-procedures it tests of still being in PHASE_NETWORK
(to close then the link) it will repend endlessly the negotiation of
the IP and the compression mode :( So it seems that there is some sort
of dis-synchronization between the state machines...

Pascal


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